1. Field of the Invention
The present invention relates to a Mold Cased Circuit Breaker (so called abbreviated as MCCB), and more particularly, to an external operating handle mechanism for a mold cased circuit breaker for operating an handle of the mold cased circuit breaker within a power distributing board or confirming an on/off state or a tripped state of the mold cased circuit breaker on a front panel of the power distributing board having the mold cased circuit breaker therein.
2. Background of the Prior Art
In general, a mold cased circuit breaker is a type of an electric apparatus using a relatively low voltage for protecting a circuit or a load by automatically breaking the circuit upon electrically occurring an overload or a short circuit. The mold cased circuit breaker typically has a case formed by molding a resin having electrical insulating properties, and thus is referred to as the Mold Cased Circuit Breaker (MCCB). A plurality of mold cased circuit breakers are installed within a power distributing board rather than being independently installed, which can be seen in many facilities consuming great power such as factories, buildings, and the like. Upon installing the mold cased circuit breakers within the power distributing board, the present invention provides a unit for operating a handle of the mold cased circuit breaker on a front panel or a door of the power distributing board which is in a state of being closed, and a unit for confirming an on/off state or a tripped state of the mold cased circuit breaker even from an outside of the power distributing board.
Hereinafter, an external operating handle mechanism of a prior art mold cased circuit breaker will now be explained in detail with reference to FIGS. 1 and 2. FIG. 1 is a side sectional view illustrating a state in which a prior art external operating handle mechanism is coupled to a mold cased circuit breaker, and FIG. 2 is a perspective view illustrating the external operating handle mechanism shown in FIG. 1 from its bottom portion.
An external operating handle mechanism 10 of the prior art mold cased circuit breaker may include a handle case 11, an external operating handle 12, a handle lever 13, and a handle plate 14. The external operating handle mechanism 10 is installed on the mold cased circuit breaker 8. The external operating handle 12 protrudes outwardly from a front panel 9 of a power distributing board (not shown).
The handle case 11 forms an appearance of the external operating handle mechanism 10, and accommodates the handle plate 14 and the handle lever 13. The handle case 11 is screw-coupled to an upper surface of the mold cased circuit breaker 8. In order to be coupled thereto, a side surface of the handle case 11 has four screw holes 11a. 
The external operating handle 12 protrudes out of the panel 9 so as to allow a user to grab and turn it at the outside of the panel 9. The external operating handle 12 is rotatably installed at an upper side of the handle case 11. In order to allow the external operating handle 11 to protrude outwardly from the panel 9, the panel 9 has a through hole (not shown) for passing a shaft of the external operating handle 12 therethrough.
The handle lever 13 is assembled into the handle case 11 using a pin 16 to be rotatable with respect to the handle case 11. A generally square shaped connecting hole 13a into which a handle (not shown) of the mold cased circuit breaker 8 is inserted is formed at a bottom surface of the handle lever 13.
Semi-circular protrusions 13a′ are formed at both sides of the connecting hole 13a so as to displace the handle of the mold cased circuit breaker 8 by a point-contact with the handle when the handle lever 13 rotates.
The handle plate 14 transfers a rotative power of the external operating handle 12 to the handle lever 13. For this, one side of the handle plate 14 is connected to the external operating handle 12 and the other side thereof is connected to the handle lever 13.
Hereinafter, an operation of the prior art external operating handle mechanism 10 having such construction as shown in FIGS. 1 and 2 will now be explained.
When the user rotates the external operating handle 12, the handle plate 14 connected to the external operating handle 12 also rotates.
In response to the rotation of the handle plate 13, the handle lever 13 rotates centered on the pin 16.
At this time, the protrusions 13a′ of the handle lever 13 are point-contacted with the handle of the mold cased circuit breaker 8 to displace the handle.
Accordingly, the user rotates the external operating handle 12 to operate the handle of the mold cased circuit breaker 8, thereby turning on/off the mold cased circuit breaker 8 at the outside of the power distributing board.
However, in the prior art external operating handle mechanism 10 of the mold cased circuit breaker as described above, a rotational center of the external operating handle 12 is different from that of the handle lever 13. Accordingly, because of the two different rotational centers, it is difficult to control a stroke required for the operation of the handle of the mold cased circuit breaker 8 and an operational range of the external operating handle 12 according to the stroke.
Also, the two rotational centers are spaced from each other, and accordingly power may be inaccurately transferred to the handle of the mold cased circuit breaker 8 from the external operating handle 12. In particular, upon operating a reset function for which a large amount of power is required, an unreasonable force is applied to the handle lever 13 or resin components of other switching mechanisms. As a result, deformation or damage may occur on the handle lever 13 or the switching mechanisms, and thus the reset operation may not be successfully done or may be performed faultily.